In the paper, the representational capacity of modified Johnson-Cook (m-JC) constitutive model on the high temperature rheological behavior of 304 austenitic stainless steel is studied. The material constants of constitutive model are calculated with the data of experimental true stress-strain for isothermal compression test at different temperatures, strains and strain rates so that the m-JC constitutive model of 304 austenitic stainless steel is established. The applicability of the model is evaluated by comparing the correlation coefficient, average relative error and mean square error of predicted results. The results showed that the average absolute relative error between the predicted results and experimental results of m-JC model was 6.77%, correlation coefficient was 0.987 as well as mean square error was 11.2 MPa so that the m-JC constitutive model could more accurately describe the rheological behavior of 304 austenitic stainless steel.

In order to achieve effective logistics control for metallurgical waste slag, the intelligent management and control system is realized, in which such transportation and sale processes as contract, plan, clean transportation, weighing, confirmation of loading and unloading in stock ground as well as automatic transportation to outside of plant are integrated through the remote access and control technology, automatic license plate recognition technology with surveillance camera at guard room and development of App on cell phone. As a result, the loopholes in the processes of sales, transportation and measurement for metallurgical waste slag are eliminated as well as the cheating behaviors are completely eradicated so that the levels of measurement control and informatization management for enterprise are improved.

The independent research and development has been carried out by Baotou Steel based on the technical requirements of hot rolled coil with high strength and corrosion resistance for railway carriages. The mechanical properties and corrosion resistance of the test steel all meet technical requirements through adopting the system of low carbon+copper chromium nickel alloy and appropriate controlled rolling and controlled cooling processes. The trial production results showed that its yield strength was 550~580 MPa, tensile strength was 645~690 MPa, elongation after fracture was 20.0%~22.0%, low-temperature impact absorbing energy at -40 ℃ was 202~255 J and microstructure at room temperature was ferrite+pearlite+bainite, which was with excellent matching of strength and toughness. Its average corrosion rate is 2.813 5 mm/a, while that of Q235B is 36.060 5 mm/a, so its corrosion rate is 7.8% of that of Q235B.

In order to study the relations between straightening process and residual stress of rails, the stress-strain situation of rails during straightening process is simulated combining with the ABAQUS software of finite element analysis. Various straightening process plans of rails are with simulation analysis to determine the optimal one and are researched combining with the results of on-site process debugging. The results showed that the minimum elastic core of each straightening plan was within deformation zoneⅡ, so the residual stress of rails could be effectively reduced by reducing the rolling reduction of 2^# and 4^# straightening rolls as well as straightening speed of rails.

In the paper, the technical requirements, production process control and quality performances of seamless steel pipe BT770 for crane boom produced by Baotou Steel are introduced. The seamless steel pipe BT770 for crane boom produced with the full process production process of “continuous casting billet+PQF continuous rolled seamless steel pipe+quenched-tempered heat treatment” and treatment process of external surface for steel pipe are with higher strength and toughness, good low temperature impact toughness, welding performances and surface quality.

In this paper, the bending and bullet-proof properties of steel plate BTP500 are tested. The results of 90° folding test for steel plate BTP500 with thicknesses of 6 mm and 9 mm meet the requirements; the tensile strength of steel plate welded with ferritic welding wire is 100 MPa higher than that of the steel plate welded with austenitic welding wire through comparing the results of performance tests for steel plate BTP500 welded with ferritic welding wire and austenitic welding wire. The impact energy of the test plate welded with ferritic welding wire at -40 ℃ is 20~30 J and the weld test of steel plate BTP500 could meet the agreement requirements. With the penetration of bullet, both of the steel plates BTP500 with thicknesses of 6 mm and 9 mm by industrial trial production are not penetrated, which are with very good bullet-proof and anti-penetration properties as well as the bullet-proof property could meet the agreement requirements.

The cracking sample of flash welded wheel steel 380CL for rim is detected and analyzed with optical microscope and microhardness tester. The results showed that the content of C in wheel steel 380CL exceeded the upper limit of internal control, heat with high temperature in the weld region during flash welding was fast, cooling speed was fast after weld, hardenability of weld region was improved and coarse bainite structure appeared; the microhardness of matrix and heat affected zone (HV0.1) was 303~310, while that of weld region (HV0.1) was 346, which was 12%~14% higher than that of matrix and heat affected zone, so the hardness difference was greater and ability of deformation coordination of each structure was poor when the rim flared and deformed so that they were cracked at the junction of weld seam and coarse grain heat affected zone. The weld microstructure could be refined, hardness difference of weld, matrix and heat affected zone could be reduced by strictly controlling the chemical compositions of wheel steel 380CL and reducing welding heat input so that good plasticity of weld could be ensured and cracking rate of forming for rim could be reduced.

The chemical composition, heating and rolling processes of hot rolled beam SM490YB are reasonably designed according to the technical standard requirements of hot rolled H beam SM490YB for offshore oil platforms in the Japanese Standard JIS G 3106-2020 “Rolled Steel for Welded Structures” combining with the characteristics of working conditions of production line in steel plant. The yield strength of the test steel with Nb-V microalloying is 412~420 MPa, tensile strength is 531~545 MPa, elongation after fracture is 26%~29%, longitudinal impact absorbing energy at -20 ℃ is greater than 200 J and transverse impact absorbing energy is greater than 110 J; microstructure of the test steel at room temperature is fine ferrite+pearlite and grain size number of ferrite is 8.5. The test results showed that the H beam with Nb-V microalloying was with good comprehensive mechanical properties, which could meet the requirements of high strength and toughness, low temperature resistance and easy to be welded for the steel for offshore oil platforms.

The effects of annealing temperature on microstructure and hardness of hot-dip galvanized low alloy high strength steel strip HC420LAD+Z are analyzed through thermal simulated test machine, optical microscope and hardness test as well as it is concluded that its recrystallization temperature is 700 ℃. The changes of microstructure and properties of the steel strip at different annealing temperatures are further discussed combining the industrial productions with the measured recrystallization temperature. The results showed that the mechanical properties of steel strip were the best when annealed at 780 ℃, yield strength was 467 MPa, tensile strength was 508 MPa, elongation was 24% and the surplus was moderate, which could meet the requirements of EN 10346-2015 standard and customer use.

In recent years, great progress has been made in the production technology of heat treatment for steel plate with limit specifications. The production technologies of heat treatment for steel plate with limit specifications at home and abroad are compared and introduced. The intensive production technology of heat treatment with roller quenching is adopted in China, the trial production of the thinnest steel plate (2 mm) as well as continuous and stable productions of the thickest steel plate (300 mm) have been achieved, which gradually surpass the production technologies of heat treatment adopted abroad, temperature control quenching and water tank quenching. As a result, significant contributions have been made to the large-scale, lightweight and long-service life equipment manufacturing as well as adapting to complex and harsh service environment in China.